In this Aug. 26, 2014 photo, Central American migrants sleep atop a moving freight train as it heads north from Arriaga toward Chahuites, Mexico. A Mexican crackdown seems to be keeping women and children off the deadly train, known as "The Beast," that has traditionally helped thousands of migrants head north. The once-open route to the United States has become so difficult that trains now carry a small fraction of the migrants they used to, and almost exclusively adult men.